The first memoir or paper published on a zoölogical subject by Lamarck was a modest one on shells, which appeared in 1792 in the _Journal d'Histoire naturelle_, the editors of which were Lamarck, Bruguière, Olivier, Haüy, and Pelletier. This paper was a review of an excellent memoir by Bruguière, who preceded Lamarck in the work of dismemberment of the Linnæan genera. His next paper was on four new species of Helix. To this _Journal_, of which only two volumes were published, Cuvier contributed his first paper--namely, on some new species of "Cloportes" (Oniscus, a genus of terrestrial crustacea or "pill-bugs"); this was followed by his second memoir on the anatomy of the limpet, his next article being descriptions of two species of flies from his collection of insects.[120] Seven years later Lamarck gave some account of the genera of cuttlefishes. His first general memoir was a prodromus of a new classification of shells (1799). Meanwhile Lamarck's knowledge of shells and corals was utilized by Cuvier in his _Tableau élémentaire_, published in 1798, who acknowledges in the preface that in the exposition of the genera of shells he has been powerfully seconded, while he indicated to him (Cuvier) a part of the subgenera of corals and alcyonarians, and adds, "I have received great aid from the examination of his collection." Also he acknowledges that he had been greatly aided (_puissamment secondé_) by Lamarck, who had even indicated the most of the subdivisions established in his _Tableau élémentaire_ for the insects (Blainville, _l. c._, p. 129), and he also accepted his genera of cuttlefishes. After this Lamarck judiciously refrained from publishing descriptions of new species, and other fragmentary labors, and for some ten years from the date of publication of his first zoölogical article reserved his strength and elaborated his first general zoölogical work, a thick octavo volume of 452 pages, entitled _Système des Animaux sans Vertèbres_, which appeared in 1801. Linné had divided all the animals below the vertebrates into two classes only, the Insecta and Vermes, the insects comprising the present classes of insects, Myriapoda, Arachnida, and Crustacea; the Vermes embracing all the other invertebrate animals, from the molluscs to the monads. Lamarck perceived the need of reform, of bringing order out of the chaotic mass of animal forms, and he says (p. 33) that he has been continually occupied since his attachment to the museum with this reform. He relies for his characters, the fundamental ones, on the organs of respiration, circulation, and on the form of the nervous system. The reasons he gives for his classification are sound and philosophical, and presented with the ease and aplomb of a master of taxonomy. He divided the invertebrates, which Cuvier had called animals with white blood, into the seven following classes. We place in a parallel column the classification of Cuvier in 1798.